Vibration Source

Defective Cage

Broken at one point

Cage broken in pieces

Broadband noise

radial

broad band

Noise due to debris from cage in the bearing

Inadequate Preload

or Lubrication

High-frequency noise "haystack"

broad band

Natural frequency of the bearing.

Bearing Looseness

turning on the shaft

No. and amplitude of the harmonics is a function of looseness.

Loose in housing

1X, 2X, 4X

radial

narrow band

Extreme Looseness

or failure

0.5X, and harmonics

Rising low frequency noise floor.

Excessive Bearing Clearance

Cocked Bearing

1X, 2X, bearing tones

axial, radial

high, steady

narrow band

180 phase difference in axial measurements on each side of bearing housing